JPH0159823B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for starting a converter in AC/DC conversion equipment directly connected to a generator.

Conventionally, the method for starting a converter is to set the control delay angle (hereinafter referred to as α) at around 90 degrees, deblock the converter at α, and after deblocking, set the control delay angle (hereinafter referred to as α) to around 90°. There is a known method for controlling the transition so that This method has the advantage of being able to relatively suppress systematic disturbances.

A block diagram in which such a system is used is shown in FIG. FIG. 1 shows a schematic configuration diagram of a DC power transmission device, in which AC buses 1, 1' are connected via converting transformers 2, 2' to a converter 3, which is composed of a large number of thyristors connected in series and parallel, for example. 3', and converts alternating current into direct current or vice versa by controlling the firing phase of each thyristor. 4 and 4' are smoothing reactors, 5 is a DC transmission line, 6 and 6' are voltage transformers (P/T), and 7 and 7' are voltage transformers (C/T).
T) is shown. The control device in such a main circuit configuration includes constant current control circuits (ACR) 8, 8', constant voltage control circuits (AVR) 9, 9', and the like. The constant current control circuit and the constant voltage control circuit convert the deviations between the reference values I _dp and E _dp and the detected values I _d and E _d into a control voltage E _c , and this control voltage E _c is sent to the control voltage selection circuit 10, 10'. The control voltage selection circuits 10 and 10' automatically select the control system that advances the control angle most among various types of control,
The control voltage E _c selected here is subjected to upper and lower limit limits in the control voltage limiter circuits 11, 11' and is input to the ignition phase control circuits 12, 12'. The ignition phase control circuits 12, 12' determine an ignition phase proportional to the control voltage E _c and output an ignition command to the thyristor. As is well known, in the AC/DC converter configured in this way, by switching the current margin (ΔI), one is operated as a forward converter under constant current control, and the other is operated as an inverse converter under constant voltage control. .

Now, in equipment with such a configuration,
FIG. 2 shows a load build-up pattern when the above-mentioned startup method is adopted. In FIG. 2, it is assumed that the current setting value I _dp at startup is 10% of the rated value.
Naturally, the smaller the current setting value I _dp , the smaller the systematic disturbance caused by converter startup. _dp cannot be lower than 10%. That is, if it is less than 10%, there is a risk that the current will be interrupted, and as a result, the thyristor element may be destroyed. Therefore, in conventional equipment, the minimum current setting value is 10%. Further, in FIG. 2, the time until the transmitted power rises to 10%, ie, _T1 , is 200ms to 300ms.

Now, in FIG. 1, consider the case where the AC bus 1 is directly connected to a generator via a step-up transformer or the like. For example, there is a case where nuclear power is transmitted to a consumption area via DC power transmission equipment. The same applies not only to nuclear power but also to thermal power. In nuclear power generation, when the rated load is taken from a no-load state, it is done slowly over a long period of time. An example is shown in FIG. As shown in FIG. 3, it is well known that in order to adjust the generator output, the adjustment valve and the bypass valve are adjusted. In other words, the steam generated in the nuclear reactor is guided to the turbine that drives the generator via the control valve, and is also led to the condenser etc. via a bypass valve installed separately from this system before the control valve. ing. Therefore, when the bypass valve is closed and the control valve is opened, the reactor output is converted to electric power via the turbine generator, so by appropriately adjusting the bypass valve and control valve, the reactor output can be adjusted as desired. can be converted into electricity. That is, at the beginning of startup, the generator output G ₁ is a few percent of the rated value, the time of T ₁ is several tens of seconds, the time from T ₁ to T ₂ is about 10 minutes, and the generator output G ₁ is a few percent of the rated value. G ₂ (usually rated number 10
%), that is, the time from T ₂ to T ₃ , is about 1 day, and the time to start up the generator output from G ₂ to the rated output, that is, from T ₄ to T ₅ , is about 1 hour.
In the case of thermal power, although it is not as strong as nuclear power,
In any case, the load is started at a speed that is incomparably slower than the load start-up speed of the DC interconnection equipment. Therefore, if the conventional startup method is adopted for DC interconnection equipment that is directly connected to a generator, the following problems will occur. As mentioned above, the DC interconnection equipment is capable of power interchange of about 10% at the time of activation, and the activation of the DC interconnection equipment for this purpose is performed at time T ₃ in Fig. 3. However, as shown in Figure 2, the time _T1 required for the transmitted power to reach 10% when the DC current is 10% and the DC voltage is 100% is 200ms to 300ms, so the control delay angle at startup is set to 90%. Even if the converter is deblocked by setting it close to α and the transition control is performed so that the predetermined α is reached after deblocking, the load on the generator suddenly increases to 10% at T3 in Figure ₃ . During this period, the electrical output becomes larger than the turbine torque that drives the generator, causing problems such as a decrease in the frequency of the system. For this reason, a new startup method is required.

Accordingly, an object of the present invention is to provide a new starting method for an AC/DC converter in a DC interconnection facility directly connected to a generator, which has been made to meet such demands.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a circuit diagram of the control voltage limiter circuit 11' in the inverter 3' of FIG. 1.
In Fig. 4, 13 is a setting device, 14 and 15 are switches, 16 is an amplifier, and 17 is a capacitor.
18 is a resistance. At the beginning of startup, the switch 14 is on, the switch 15 is off, and the setting device 13 is set to α.
The output from the control voltage output circuit 10' shown in FIG. 1 is input to the amplifier 16 via the switch 15. Therefore, at the beginning of startup, the converter is operated at around α=90°. That is, the DC voltage is approximately zero. In this state, the operation is continued until the generator output rises to about 10%, and when the generator output reaches about 10%, switch 14 is turned off and switch 15 is turned on to move to steady operation. .

Next, we will discuss the effect.

If such a startup control method is used, the DC voltage of the DC power transmission device shown in FIG. 1 is approximately zero at the beginning of startup, so the transmitted power is approximately zero. Therefore, there is no problem on the generator side, and the steam generated in the reactor during that time is bypassed via the bypass valve. After that, when the reactor output reaches nearly 10%, the bypass valve is closed and the control valve is opened to shift to steady operation according to the valve operation speed. In this case, the constants of the capacitor 17 and resistor 18 in FIG. 4 are selected to match the transition speed.

The activation control method described above is the simplest method, but a more detailed activation control method will be explained next. Normally, on the generator side, an initial load of about several percent is allowed. Therefore, the allowable initial load of the generator is set to 5%. In Figure 1, the current setting value
Start by setting I _dp to 10% and voltage setting value E _dp to 50%. In this way, the DC power transmission device in FIG. 1 will transmit 5% of the power.
Thereafter, the voltage setting value is increased in accordance with the generated power value on the power generation side and shifted to the rated DC voltage.

As described above, the present invention has the immeasurable effect of enabling a DC interconnection system directly connected to a generator by performing zero power factor operation or reduced DC voltage operation at startup.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of DC power transmission, Fig. 2 is a diagram showing the start-up pattern of conventional conversion equipment, and Fig. 3 is a diagram showing the load start-up pattern of nuclear power generator output.
FIG. 4 is a circuit diagram showing one embodiment of the present invention. 1, 1'... AC bus, 2, 2'... Conversion transformer, 3, 3'... Converter, 4, 4'... Smoothing reactor, 5... DC transmission line, 6, 6'... ...Instrument transformer (P/T), 7,7'...Instrument current transformer (C/T), 8,8'...Constant current control circuit, 9,
9'... Constant voltage control circuit, 10, 10'... Control voltage selection circuit, 11, 11'... Control voltage limiter circuit, 12, 12'... Firing phase control circuit, 13
... Setting device, 14, 15 ... Switch, 16 ...
Amplifier, 17... capacitor, 18... resistor.

Claims (1)

[Scope of Claims] 1. An AC/DC converter is provided at each end of a DC transmission line, different AC systems are interconnected, and at least one of the AC systems is provided with a turbine generator equipment, and the turbine generator equipment is equipped with a turbine generator equipment. In a method of starting an AC/DC converter when generating power is gradually increased, a portion of the steam sent to the turbine generator via the bypass valve is used until the output of the equipment that sends the steam to the turbine generator reaches a predetermined value. is bypassed, the AC/DC converter is operated at a control delay angle of approximately 90° during this period, and the bypass valve is operated in the direction of closing from the time when the output of the equipment that sends steam to the turbine generator exceeds a predetermined value. , the AC/DC converter on the turbine generator equipment side is under constant current control, the AC/DC converter on the other end is under constant voltage control, and the current setting value of the AC/DC converter on the turbine generator equipment side and the AC/DC converter on the other end are controlled. A method for starting an AC/DC converter, characterized in that a voltage setting value is increased in accordance with an increase in power generated by the turbine generator equipment. 2 An AC/DC converter is provided at each end of a DC transmission line, different AC systems are interconnected, and at least one of the AC systems is equipped with generator equipment, and the power generated by the generator equipment is adjusted to the rated power generated. In the startup method of an AC/DC converter when the power is gradually increased from a minimum power of about a few percent, the current setting value of the AC/DC converter on the generator equipment side that is controlled by a constant current and the AC/DC converter at the other end that is controlled by a constant voltage are determined. An AC/DC converter, characterized in that the product of the conversion device and the voltage setting value is set to the minimum power, and the setting value is increased in accordance with an increase in the power generated by the generator equipment. Starting method.